Positive indicators include metrics such as read and forwarded messages, along with messages replied to and those marked as “not spam”. Such actions act as indicators of subscriber engagement, with these tracked by several mailbox providers. Negative indicators include messages marked as spam along with messages deleted before reading.

Below, some highlights across these indicators, based on Return Path’s analysis of global consumer data comprising more than 17,000 commercial senders, 2 million consumer panelists and more than 5.5 billion commercial email messages sent to Microsoft, Gmail, Yahoo and AOL users throughout 2017.

Spam Placement Rate

This metric is key to knowing what type of trust is placed in senders, with spam placement affected by factors including the content, sender reputation and subscriber engagement .

On average, 13.5% of emails sent last year were delivered to the spam folder, representing a slight increase from 2016 (12.5%).

That 13.5% average masked some significant variances across industries.

The verticals with the best spam placement rate (i.e., the lowest), included Distribution & Manufacturing (3.5%, down from 6% in 2016), Banking & Finance (5.7%, relatively flat), Insurance (8.2%, down from 10.9%) and General Merchandise (9.7%, up from 7.5%).

By comparison, senders in the Education/Non-Profit/Government (23.7%, up from 20.3%), Social & Dating (20.7%, up from 19.6%) and Sporting Goods (18.6%, up from 16.3%) sectors had rates multiple times higher than the most trusted senders.

In terms of year-over-year trends, the Telecommunications industry fared best, with its spam placement rate plummeting from 21.8% in 2016 to 12.1% last year. The Pets category (15.3%, up from 10.9%) had the largest increase in spam placement rate.

This Is Not Spam Rate

This is a significant metric as it could “indicate a false positive with the spam filter”. It can be difficult to ascertain what constitutes a good metric here, though, as a higher “this is not spam” rate could be the result of more emails being placed in the spam folder. Yet generally speaking this can be seen as a positive indicator as a selection suggest that subscribers are willing to search through a spam folder to rescue an email.

With that said, industries with a high spam placement rate and low “this is not spam” rate should be concerned as this could reflect a lack of interest or awareness from recipients.

Industries combining above-average spam placement rates with below-average “this is not spam” rates this past year included Social & Dating, Business & Marketing, Media & Entertainment, and Automotive.

The overall rate was 1.77% across industries, up from 1.04% in 2016 and from 0.03% in 2015.

Read Rate

Return Path argues that read rate (% of messages sent that are read) is a more accurate metric than open rate, because it looks at all emails that are viewed regardless of whether or not images are rendered.

Email marketers saw a slight decline in the overall read rate last year, down to 21.5% from 22.2% in 2016, though remaining well above 2015’s rate (14%).

The Distribution & Manufacturing (57.7%) sector was the most impressive performer again in 2017, with more than half of its emails sent being read. Insurance (39%) and Banking & Finance (36.1%) also enjoyed read rates well above the average, a finding supported by Epsilon research showing above-average engagement with financial industry emails, perhaps due to their having a higher incidence of triggered messages, which typically see higher response rates.

Meanwhile, Business & Marketing (15%), Education/Non-Profit/Government (15.5%), Social & Dating (16.6%) emails were the least enticing to recipients, as they were in 2016.

In terms of year-over-year trends, the Telecommunications sector had the biggest improvement, albeit a slight one (from 31.5% to 33.3%), while the Office Supplies vertical was among the many to show a drop-off (21.3%, down from 24.3%).

Delete Before Reading Rate

In 2016, 1 in 8 (12.5%) of emails sent were deleted without being read, per Return Path data. That rate improved very slightly in 2017, falling to 11.9%.

Return Path indicates that consistently high rates in this area may signal dissatisfaction with an overall email marketing campaign, and that this metric can reflect inbox (lack of) desirability. A rate that is too high could result in more future emails being directed to the spam folder.

That could be worrisome for senders in the Household & Home Improvement (14.8%), Office Supplies (14.2%), Pets (14.2%), and Flowers & Gifts (14.1%) verticals, which had the highest delete-before-reading rate. It could be that recipients of these emails had signed on to a list for a one-off purchase, and were not interested in future emails.

By contrast, more account-focused industries such as Distribution & Manufacturing (5.9%), Social & Dating (9%), Technology/Software/Internet (9.1%) and Insurance (9.4%) had the lowest rates. It’s interesting to see that the Social & Dating vertical had a below-average rate given that it was one of the worst performers in terms of read rate.

Reply Rate

Very few marketing emails generate replies, and Return Path does mention that there’s no target rate here as a high reply rate could signal either a positive (engaged list) or negative (subscribers trying to unsubscribe) reaction to email. Even so, a reply is a sign of engagement, and the analysts recommend switching from a “noreply@” address to a managed address.

Overall, just 0.11% of emails were replied to last year, inching down from 2016’s 0.13%.

Once again, the more account-based industries, such as Telecommunications (2.16%) and Insurance (1.93%) had the highest reply rates, whereas verticals such as Toys/Hobbies/Crafts (0.02%), Kids & Babies (0.02%) and Social & Dating (0.02%) generated virtually no replies at all.

Forward Rate

Reply rates might be low, but forward rates are even lower. This is an area that could be important for marketers in growing their lists. It is a strong indicator of an engaged list, and shows that the content being sent is relevant not only to the recipient but also to the recipient’s network.

Still, just 0.02% of emails sent last year on average were forwarded by recipients. The same industries leading the way in reply rate topped the list in forward rates: Insurance (0.16%); Telecommunications (0.15%); and Distribution & Manufacturing (0.15%).

By contrast, the Social & Dating and Deals & Rewards verticals saw a 0.00% forward rate.

Complaint Rate

This is perhaps the most negative of all metrics, as it demonstrates a direct action by the recipient demonstrating that the email is not desired. As such, it is heavily factored by mailbox providers into filtering decisions.

Luckily for marketers, this rate improved in 2017 (0.17%) in comparison to the year before (0.19%).

“Return Path conducted this study using global consumer data consisting of over 17,000 commercial senders, 2 million consumer panelists, and over 5.5 billion commercial email messages sent to Microsoft, Gmail, Yahoo, and AOL users between January 1, 2017, and December 31, 2017.

Consumer data is Information captured from monitored email accounts controlled by real subscribers to sample user initiated and engagement based filtering decisions by mailbox providers. Consumer data can uncover behavior based factors and thresholds that influence inbox placement at large mailbox providers, and can’t be identified by non-interactive seeds.”